Note: Descriptions are shown in the official language in which they were submitted.
CA 02853493 2014-04-24
WO 2013/074413 PCT/US2012/064413
1
WIRELESS FLOW MONITORING DEVICES
FIELD OF THE DISCLOSURE
[0001] This patent relates generally to flow control devices and, more
particularly, to
wireless flow monitoring devices.
BACKGROUND
[0002] The flow of material (e.g., fluids, solids, etc.) in pipelines or
other conduits is
an important function in modern industrial and commercial processes. In many
settings, it is
important to monitor and detect whether material is flowing in a pipeline or
other conduit and
to respond in accordance with an overall control strategy. In many
applications, one or more
flow switches may be used for this purpose.
[0003] Many known flow switches function to complete (make) or interrupt
(break)
an electrical circuit when a flow or a no-flow condition is detected within a
pipeline. Cables
wired to the electrical circuit may electrically couple the flow switch to a
process controller, a
motor or pump, and/or any other device within a process control system to
provide or assert a
signal when flow stops, remove or shut off a signal when flow is adequate,
start a motor in
response to detecting a flow, stop a motor in response to a no-flow condition,
or implement
any other appropriate action.
SUMMARY
[0004] Wireless flow monitoring devices are described. In one example, a
device to
wirelessly monitor a flow of material is described that includes a housing
having a first
surface and a second surface opposite the first surface, the second surface
having an aperture.
A lever is secured within the housing to in response to the flow of material,
where a portion
of a first arm of lever is formed from a paddle arm, where an end of the
paddle arm extends
out the aperture of the second surface of the housing, and where a paddle is
affixed to the
paddle arm to be positioned within the flow of material. The device includes a
magnet that is
actuated by a second arm of the lever to move an amount proportional to the
first arm of the
lever, a portion of the magnet extending beyond the first surface of the
housing, and a
wireless position monitor mounted to the first surface of the housing so that
a motion path of
the portion of the magnet extending beyond the first surface of the housing is
disposed within
CA 02853493 2014-04-24
WO 2013/074413 PCT/US2012/064413
2
a channel in the base of the wireless position monitor, where the channel
serves as a sensor to
detect movement of the magnet.
[0005] In another example, a wireless flow monitoring device includes an
enclosure
having a bottom surface and a top surface, a paddle arm coupled to the
enclosure and
extending out an opening in the bottom surface of the enclosure, and a paddle
affixed to the
paddle arm, the paddle and the paddle arm forming a first lever arm to rotate
about a pivot
point within the enclosure in response to material flowing within a pipe. The
device also
includes a second lever arm to rotate about the pivot point an amount
proportional to the
rotation of the first lever arm, a portion of the second lever arm extending
beyond the top
surface of the enclosure, the portion of the second lever arm having a
magnetic array to be
positioned within a sensor channel of a wireless position monitor to detect
movement of the
magnetic array.
[0006] In yet another example, a flow monitoring device includes a
housing having a
cavity formed by a base and a cover, a hollow body affixed to the base about
an opening in a
first surface of the base, the hollow body enabling the device to be installed
on a conduit
through which material flows, the flow of the material being monitored by the
device, and a
paddle arm extending through the opening in the first surface of the base
through the hollow
body, the paddle arm being coupled to the housing to enable the paddle arm to
rotate in
response to the flow of the material within the conduit. The device further
includes a paddle
affixed to paddle arm and positioned within the conduit and a magnet extending
from the
pivot joint in a direction substantially opposite the paddle arm to rotate an
amount
proportional to the rotation of the paddle arm, the magnet extending beyond a
top surface of
the housing to enable a position monitor to be mounted to the device to
monitor the flow of
the material by monitoring the rotation of the magnet.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] FIG. 1A is an illustration of a known paddle type flow switch.
[0008] FIG. 1B is an exploded view of the known flow switch shown in FIG.
1A.
[0009] FIG. 2A is a front view of an example flow switch attached to a
wireless
position monitor in accordance with the teachings of this disclosure.
[0010] FIG. 2B is a back view of the example flow switch in FIG. 2A
attached to the
wireless position monitor.
[0011] FIG. 2C is another view of the example flow switch in FIG. 2A
attached to the
wireless position monitor.
CA 02853493 2014-04-24
WO 2013/074413 PCT/US2012/064413
3
[0012] FIG. 3 is another known paddle type flow switch shown in
disassembled form.
[0013] FIG. 4A is an example paddle type flow switch in accordance with
the
teachings of this disclosure that is placed next to a wireless position
monitor.
[0014] FIG. 4B is an enlarged view of the example flow switch and
wireless position
monitor of FIG. 4A.
[0015] FIG. 4C depicts a portion of the example flow switch and wireless
position
monitor of FIG. 4A.
[0016] FIG. 5 is an illustration of an example fully-assembled flow
switch according
to the teachings of this disclosure.
[0017] FIG. 6 depicts a top surface of the wireless position monitor
shown in FIGS. 2
and 4.
DETAILED DESCRIPTION
[0018] In accordance with many known approaches, a flow switch may be
integrated
within a process control system by physically wiring the flow switch into the
control system.
Such wiring can incur significant costs, both upfront during set up and
installation, as well as
during ongoing maintenance. These known approaches may require a lot of
electrical
wires/cables and/or may increase the amount and/or the size of conduits used
to run the wires
within the process control system as well as the sizes of cable trays. Also,
wiring can be
costly and/or impractical in locations that are difficult to access and
install the wiring.
Furthermore, additional wiring in a process control system may require
expansion cards for a
process controller to provide additional input points to connect each wire to
the controller to
enable all components to properly communicate, thereby incurring additional
cost and/or
inconvenience. Additionally, electrically wiring a flow switch may not be
approved for use
in hazardous (classified) areas where unsafe environments (e.g., class I -
flammable gases or
vapors, class II - combustible dust, etc.) pose a risk of explosion or other
danger.
[0019] The foregoing problems may be alleviated by communicating the flow
monitored by flow switches via intrinsically safe wireless technology. By
wirelessly
communicating the flow measured by a flow switch, it is possible to eliminate
the labor and
expense of installing electrical cables, running the cables across a process
space through
conduits, and finding available input points to physically terminate the wires
with
connections to a controller and/or other device. Instead, a single gateway may
receive
wireless signals from multiple components and communicate each of those
signals via Hart,
OLE for Process Control (OPC), modbus Ethernet, serial 485, or any other
communication
CA 02853493 2014-04-24
WO 2013/074413 PCT/US2012/064413
4
protocol without the need for discrete input cards to receive separate wires
from each
additional component. Furthermore, monitoring flow without hardwired flow
switches
enables the monitoring of material flow at locations that would be otherwise
difficult and/or
impractical to access via many known methods.
[0020] Additionally, many known implementations of wireless technology
include
wireless devices designed to be intrinsically safe so as to be approved for
use in hazardous
(classified) environments. For example, it is known that an intrinsically safe
wireless
position monitor may be attached to a control valve to detect movement of the
valve shaft or
stem to determine the position of the valve and communicate the position back
to a controller
without the need to run physical wires in a process space. However, many of
the known flow
switches cannot be connected to wireless position monitors in a manner that
enables the
position monitors to obtain a reliable reading of the flow switch. As such,
with these known
approaches, the only recourse is to either physically wire a flow switch to a
process control
system (with all its related costs and limitations on the type of environment)
or to forego
measuring flow at that particular location within the process control system.
[0021] FIGS. lA and 1B illustrate a known paddle type flow switch 100.
Specifically, FIG. lA illustrates the flow switch 100 completely assembled
with a cover 102
and FIG. 1B illustrates an exploded view of the flow switch 100 without the
cover 102 to
show the internal components of the flow switch 100. The flow switch 100 is
similar in some
respects to the flow switch described by Shafique et al. in U.S. Patent No.
6,563,064, which
is hereby incorporated herein by reference in its entirety. While a complete
description can
be obtained from Shafique et al., in summary, the flow switch 100 includes a
paddle 104
attached to a paddle arm 106 that extends through a pipe adapter 108 and
through an opening
110 of a bracket, base, or housing 112 of the flow switch 100. In use, the
flow switch 100 is
coupled to a pipe (piper used herein includes pipe or any other conduit) with
the paddle 104
extending into the pipe to interact with material in the pipe. The paddle 104
and paddle arm
106 are configured to act as a first lever arm 114 that is moved or displaced
by a change in
the flow of material in the pipe to actuate a second lever arm 116 that
engages or actuates an
electrical switch 118 (e.g., a snap switch). Once engaged, the electrical
switch 118 may
provide a signal (e.g., a contact closure) to a component in a process control
system that has
been physically wired to the flow switch 100.
[0022] FIGS. 2A-2C depict an example flow switch 200, which may be
similar in
some respects to the flow switch 100 shown in FIGS. lA and 1B. However, the
flow switch
200 has been modified as discussed below.
CA 02853493 2014-04-24
WO 2013/074413 PCT/US2012/064413
[0023] Attached to a second lever arm 201 is an array of magnets 202
(which may be
referred to as a target array) configured to extend beyond the top of the base
112. By
coupling, either directly or indirectly, the target array 202 to the second
lever arm 201, the
target array 202 acts as an extension of the second lever arm 201 and moves
about a fulcrum
of the lever an amount proportional to the movement of the paddle 104 when
flow conditions
within a pipe change. The target array 202, which extends beyond the top of
the base 112, is
configured to be positioned within a channel 204 of a wireless position
monitor 206 such that
when the target array 202 moves along the channel 204, the position monitor
206 can
measure that movement to indicate the material flow conditions within a pipe.
While the
position monitor 206 may detect smaller movements, the target array 202 may
span at least
1/4" along the channel 204. To ensure accurate and reliable measurements, the
position
monitor 206 may be securely mounted to the flow switch 200 via, for example, a
bracket 208.
Once movement of the paddle 104 has been detected via the position monitor 206
detecting
movement of the target array 202, the position monitor 206 may wirelessly
transmit the
collected data to a process controller and/or other device for analysis and/or
other response.
[0024] FIG. 3 depicts another known paddle type flow switch 300 shown in
disassembled form. The flow switch 300 of FIG. 3 is similar to the flow
switches described
by Garvey in U.S. App. Pub. No. 2008/0258088, which is hereby incorporated
herein by
reference in its entirety. While a complete description can be obtained from
Garvey, in
summary, the flow switch 300 includes a paddle 302 attached to a paddle arm
304 that
extends inside a pipe adapter 308 and connects to a pivot pin or rod 306 that
extends across
the pipe adapter 308 through an aperture 310. A lever arm 312 is coupled to an
end of the
pivot rod 306 to rotate about the pivot rod 306 an amount proportional to the
rotation of the
paddle arm 304 when a change in flow of material in a pipe causes the paddle
302 to move.
The movement of the lever arm 312 is configured to actuate an electrical
switch 314 (e.g., a
snap switch), which may be physically wired to communicate with other
components in a
process control system.
[0025] FIGS. 4A-4C depict another example paddle type flow switch 400,
which is
similar in some respects to the flow switch 300 shown in FIG. 3. However, the
flow switch
400 has been modified as discussed below. A target array 402 is coupled either
directly or
indirectly to an end of the pivot rod 306 to rotate about the pivot rod 306 an
amount
proportional to the movement of the paddle 302. The wireless position monitor
206 may be
mounted to the flow switch 400 to securely position the target array 402
within the channel
204 (shown in FIG. 4C) of the position monitor 206. To position the target
array 402 within
CA 02853493 2014-04-24
WO 2013/074413 PCT/US2012/064413
6
the channel 204 of the position monitor 206, the target array 402 may be
configured to extend
beyond the top of a base 404 of the flow switch 400. This configuration of the
target array
402 and the base 404 is not shown in the figures, nor is a mounting system
shown. However,
the flow switch 400 may be modified in accordance with the discussion relating
to FIGS. 2A-
2C above to achieve the same result.
[0026] FIG. 5 depicts an example flow switch 500 according to the
teachings of this
disclosure. As with known flow switches, the example flow switch 500 includes
a cover 502
that attaches to a base 504. However, the cover 502 is adapted to provide
space for a target
array 506 to extend beyond the top of the flow switch 500 via a notch or slot
508. This
allows the target array 506 to pass through the channel 204 of the position
monitor 206
(shown in FIGS. 2 and 4) for reliable monitoring of the flow switch 500.
Furthermore, the
cover 502 also includes holes 510 to enable the position monitor 206 to be
secured to the
flow switch 500. Additionally, the cover 502 may be flat to facilitate the
mounting of the
position monitor 206.
[0027] The example cover 502 of the flow switch 500 may be applied to
either of the
example flow switches 200 or 400 described above. Furthermore, an alternative
configuration (not shown) of the example cover 502 may include a hollow
protrusion in
which the target array 506 may sit. Such a protrusion may be dimensioned to
fit within the
channel 204 of the position monitor 206 to enable the internal mechanisms of
the flow switch
500 to be completely enclosed.
[0028] Similarly, the example flow switches 200, 400, and 500 disclosed
herein are
provided by way of example only. Any other configuration of the base (e.g.,
the base 112 of
FIG. 2A), the lever arms (e.g., the second lever arm 116 of FIG. 2A), the
target array (e.g.,
the target array 202 of FIG. 2A), the cover (e.g., the cover 502 of FIG. 5)
and/or the method
of mounting the position monitor 206 that is similar to that which is
disclosed herein is
contemplated by this disclosure. For example, while FIGS. 2 and 4 show the
flow switches
200 and 400 without an associated electrical switch (e.g., the switch 118
shown in FIG. 1A),
the example flow switches 200 and 400 may be configured to include an
electrical switch 118
as well as a target array (e.g., the target array 202) to enable hardwired
and/or wireless
implementations of the flow switches 200 and 400.
[0029] Furthermore, the example flow switches 200, 400, and 500 described
herein
may be implemented in virtually any process control system. For instance, the
example flow
switches described herein may be applied to conditions of both vacuum and
positive flow in
either batch or continuous processes. Furthermore, the example flow switches
described
CA 02853493 2014-04-24
WO 2013/074413 PCT/US2012/064413
7
herein are suitable for detecting the flow of virtually any material including
liquids, gases,
and/or powder/dust.
[0030] FIG. 6 depicts a top surface 602 of the wireless position monitor
206 shown in
FIGS. 2 and 4. In particular, FIG. 6 shows a model 4310 Wireless position
monitor made by
Top Worx Inc., a subsidiary of Emerson Electric Company. However, the
teachings of this
disclosure may be implemented using any other wireless position monitor. Use
of the
wireless position monitor 206 enables the use of flow switches (e.g., the
example flow
switches 200 and 400) in virtually any location without the need to run
electric wires and/or
conduit throughout a process control system. Not only may this provide
significant cost
savings in installation and maintenance, it also simplifies the linking of
multiple devices to a
controller because a single gateway can receive numerous wireless signals,
whereas
hardwiring multiple devices requires each device to have an independent input
point.
[0031] Additionally, wireless position monitors, such as the monitor 206,
are
intrinsically safe. Thus, these wireless position monitors are approved for
any environment
(i.e., both hazardous and non-hazardous work conditions). More specifically,
these wireless
position monitors can be implemented with the disclosed example flow switches
200 and 400
in any environment because the flow switches 200 and 400 are purely mechanical
devices
that do not require any electrical connections unlike many known flow
switches. This is
made possible by the linkage-less and/or non-contact detection of movement of
the target
arrays 202 and 402 by the position monitor 206. Furthermore, not only is the
position
monitor 206 intrinsically safe during operation, it may have intrinsically
safe power modules
(i.e., batteries). As a result, if allowed under standard operating procedures
of the particular
process system, a user may change the power modules in the field without the
need for
obtaining a hot work permit. Alternatively, the position monitor 206 may use
local power to
power its operation. While this implementation requires a power cord, it still
avoids the use
of wiring electrical cables up as with many other known flow switches.
